Coiled sheet graft for single and bifurcated lumens and methods of making and use

ABSTRACT

A prosthesis is provided for treating aneurysms, occlusive disease of vessels and body organs, and arterio-venous fistulas, occurring in single and bifurcated lumens. The prosthesis comprises an expandable coiled sheet portion having a biocompatible graft, either a sheet or tube, affixed thereto along part or all of the circumference of the coiled sheet portion. The prosthesis has a small delivery profile, making it suitable for use in a variety of body vessels. Methods of making and deploying the prosthesis in single and bifurcated lumens are also provided.

This application is a continuation of application Ser. No. 10/224,094,now U.S. Pat. No. 6,793,672 filed Aug. 19, 2002, which is a continuationof application Ser. No. 09/547,247 filed Apr. 11, 2000, now U.S. Pat.No. 6,458,152, which is a continuation of application Ser. No.09/047,805, filed Mar. 25, 1998 now U.S. Pat. No. 6,048,360, which is acontinuation-in-part of application Ser. No. 08/820,213, filed Mar. 18,1997 now U.S. Pat. No. 5,824,054, the disclosure of which is expresslyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to prostheses for treatment of aneurysms,arterio-venous fistulas, obstructive vascular disease and otherapplications. More specifically, the present invention relates toprostheses including coiled sheet portions having a biocompatiblematerial affixed thereto which may be used in a variety of applicationsas an internal bandage.

BACKGROUND OF THE INVENTION

Millions of people worldwide are afflicted each year with vasculardiseases, ranging from vascular obstructive disease, such asarteriosclerosis, to diseases that weakened the arteries or othervessels, resulting in potentially fatal aneurysms and arterio-venousfistulas. Arterio-venous fistulas commonly occur other than byprogression of natural disease, for example, as a result of accidentsand gun-shot wounds. Each of these diseases has lead to the developmentof specialized treatments ranging from minimally-invasive

For example, a health problem afflicting an older segment of thepopulation is the occurrence of disease that weakens the arteries andother body vessels, developing into aneurysms that may rupture, oftenwith fatal consequences. A conventional treatment of aneurysms,especially those occurring in the abdominal aorta, has involved invasivesurgery to resect and remove the diseased body vessel and replace itwith either a native vessel, harvested from elsewhere in the body, or asynthetic graft material. Such treatments typically pose a major risk tothe patient's health, and frequently cannot be undertaken at all, if (asis common) the patient is in poor health.

A number of vascular prostheses have therefore been developed thatpermit a synthetic graft to be placed transluminally within theaneurysm, to isolate the aneurysm from fluids flowing in the body vesseland which relieve pressure from the aneurysm. These previously knownvascular prostheses generally anchor a tubular synthetic graft insidethe body vessel, on either end of the aneurysm, using a stent, asdescribed, for example, in U.S. Pat. No. 5,078,726 to Kreamer and U.S.Pat. No. 5,219,355 to Parodi et al.

Similarly, U.S. Pat. No. 5,456,713 to Chuter and U.S. Pat. No. 5,275,622to Lazarus describe stent-graft combinations, delivered transluminally,comprising a tubular graft having barbed self-expanding anchors securedby sutures to the ends of the tubular graft. U.S. Pat. No. 5,366,473 toWinston et al. describes a stent graft combination wherein a tubulargraft has a self-expanding coiled sheet stent riveted to either end ofthe graft.

wherein a tubular graft has a self-expanding coiled sheet stent rivetedto either end of the graft.

A drawback of the foregoing stent-graft systems is that they generallyrequire a large access site (e.g., 16-22 Fr), which limits theapplicability of such devices to larger vessels. Specifically, the graftmaterial generally must be bunched or gathered to fit within thedelivery system, as described in the above-mentioned Chuter, Winston etal. and Lazarus patents, but cannot be compacted within the deliverysystem, or problems may arise relating to unfurling of the graft duringdeployment. In addition, clinical testing of previously-knownstent-graft combinations has revealed problems with inadequate sealingbetween the graft material and the anchors, and where the graft contactsthe body lumen proximally and distally of the aneurysm.

Other arrangements for isolating aneurysms are also known. U.S. Pat. No.4,577,631 to Kreamer describes a method of gluing a graft across ananeurysm using a biocompatible adhesive. U.S. Pat. No. 4,617,932 toKornberg describes a bifurcated graft that is engaged to a vessel wallusing hooks. U.S. Pat. No. 5,575,817 to Martin describes a bifurcatedgraft where an extension is added to one of the legs of the graft aftera main body of the graft has been deployed. U.S. Pat. No. 5,211,658 toClouse describes a stent-graft combination wherein a temperatureactivated skeleton is first deployed in a body lumen so that it spans ananeurysm; a graft then is affixed to the deployed skeleton. U.S. Pat.No. 5,405,379 to Lane describes a polypropylene sheet which is rolledinto a coil, and permitted to self-expand within the body lumen so thatit spans the aneurysm. U.S. Pat. No. 5,100,429 to Sinofsky et al.describes a coiled sheet stent including a layer of collagen-basedmaterial which is heated by an energy source so that it fuses to form arigid structure.

Each of the foregoing arrangements has inherent disadvantages peculiarto their designs that makes the use of such designs impractical. Thesedisadvantages range from the mechanical complexity of the Kreamer,Clouse and Sinofsky et al. designs, to the inability to obtain anadequate seal at ends of the device, as in the Kornberg, Martin and Lanedevices.

With respect to treatment of obstructive vascular disease, a number ofprostheses have been developed for intraluminal deployment. Thesedevices, of which the Palmaz-Schatz stent sold by Cordis Corporation,Miami Lakes, Fla., is typical, treat obstructive disease, for example,in the coronary arteries, by retaining the patency of vessel followingan angioplasty procedure. Most previously known prostheses designed totreat obstructive disease include a plurality of throughwall openings topromote cellular proliferation. A drawback of such designs, however, isthat the openings may also promote re-formation of the obstruction overtime.

Previously known techniques for treating arterio-venous fistulas, whichpermit oxygenated blood to be shunted from an artery directly to thevenous system, typically involve open surgery. Thus, for example, agun-shot victim, given the present state of the art, must undergosurgery to repair an arterio-venous fistula. The present state-of-theart lacks any devices which may be readily deployed, even on an interimbasis, to prevent excessive blood loss while awaiting surgery.

In view of the foregoing, it would be desirable to provide a prosthesisfor treating aneurysms, obstructive disease of vessels and body organs,and arterio-venous fistulas, that is simple in design and easilydeployed.

It would further be desirable to provide a prosthesis for treatinganeurysms, obstructive disease of vessels and body organs, andarterio-venous fistulas, that overcomes problems associated with thebulkiness of prior art stent-graft systems, and that can be readilyscaled for use in a variety of vessels, thereby enabling treatment ofdisease in even very small body lumens.

It would further be desirable to provide a prosthesis for treatinganeurysms, obstructive disease of vessels and body organs, andarterio-venous fistulas, that may be readily deployed in a bifurcatedvessel.

It would still further be desirable to provide a prosthesis for treatinganeurysms, obstructive disease of vessels and body organs, andarterio-venous fistulas, that provides an internal bandage, for example,that can stem blood loss through an arterio-venous fistula, or provide apositive seal at the ends of a graft to reduce bypass flow.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide a prosthesis for treating aneurysms, obstructive disease ofvessels and body organs, and arterio-venous fistulas, that is simple indesign and easily deployed.

It is another object of this invention to provide a prosthesis fortreating aneurysms, obstructive disease of vessels and body organs, andarterio-venous fistulas, that overcomes problems associated with thebulkiness of prior art stent-graft systems, and that can be readilyscaled for use in a variety of vessels, thereby enabling treatment ofdisease in even very small body lumens.

It is a further object of the present invention to provide a prosthesisfor treating aneurysms, obstructive disease of vessels and body organs,and arterio-venous fistulas, that may be readily deployed in abifurcated vessel.

It is a yet further object of the invention to provide a prosthesis fortreating aneurysms, obstructive disease of vessels and body organs, andarterio-venous fistulas, that provides an internal bandage, for example,that can stem blood loss through an arterio-venous fistula, or provide apositive seal at the ends of a graft to reduce bypass flow.

These and other objects of the invention are accomplished by providing aprosthesis comprising a coiled sheet portion having biocompatible graftmaterial affixed thereto, so that the graft material is at leastpartially wound within the coiled sheet portion when it is contracted toits delivery state. The graft material may comprise a sheet or tube thatis affixed along a part or all of the circumference of the coiled sheetportion, and serves to alter flow to a portion of a body lumen in whichthe prosthesis is deployed. The graft may be affixed to an interior orexterior surface of the coiled sheet portion, or may comprise severallayers. The prosthesis may be configured for use in a single orbifurcated organ or vessel.

In a preferred embodiment, the coiled sheet portion of the prosthesiscomprises a mesh formed from a shape-memory alloy, such as anickel-titanium alloy, that exhibits super-elastic behavior at bodytemperature. The coiled sheet preferably includes one or more rows oflocking teeth along a longitudinal edge that interengage the mesh toretain the prosthesis at a desired expanded diameter. In addition, themesh may include a plurality of radially outwardly directed projectionsalong one or both ends that engage an interior surface of a body lumen.

The mesh of the coiled sheet may have a size suitable for use in smallerbody arteries, such as the coronary arteries and carotid arteries, ormay be scaled to accommodate larger vessels such as the abdominal aortaand iliac arteries. For larger vessels, the mesh of the coiled sheet mayinclude articulations to assist in maneuvering the prosthesis throughtortuous body passageways.

The graft material used in the prosthesis of the present invention maybe either fluid impermeable, for example, for treating arterio-venousfistulas or semi-permeable, for example, to permit nourishment of vesselintima when treating occlusive vascular disease while reducingthroughwall cell proliferation. The graft material may also beimpregnated with one or more drugs to achieve to provide a desiredeffect. The graft material may also serve to reduce embolization offrangible material from the interior of body lumen following, forexample, an angioplasty procedure.

In addition to the foregoing applications, a pair of prosthesesconstructed in accordance with the present invention may beadvantageously employed, one at either end, for positively sealing theends of a conventional tubular graft.

Methods of making and deploying the prosthesis of the present inventionin single and bifurcated lumens are also provided. In accordance withthese methods, the prosthesis is first deployed in a body lumen from areduced delivery state. A dilatation element is then disposed within theprosthesis and expanded, thereby locking the prosthesis at an expandeddiameter and positively sealing the graft material against the interiorsurface of the body lumen.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments, in which:

FIG. 1 is a perspective view of an illustrative prosthesis constructedin accordance present invention;

FIGS. 2A and 2B are end views showing the prosthesis of FIG. 1 in itscontracted state and expanded state, respectively.

FIG. 3 is a plan view of the prosthesis of FIG. unrolled during a stepof manufacturing;

FIGS. 4A-4F are cross-sectional views taken along view line 4-4 of FIG.3 and a plan view (FIG. 4D) of alternative embodiments of a prosthesisconstructed in accordance with the present invention;

FIGS. 5A-5C are views showing the steps of deploying the prosthesis ofFIG. 1 to span an idealized aneurysm in a single lumen;

FIGS. 6 and 7 are plan views of alternative articulated mesh designssuitable for use with the prosthesis of the present invention; and

FIGS. 8A and 8B are perspective and plan views, respectively, of aprosthesis employing a coiled sheet mesh designed for large vessels, inwhich the detail of FIG. 8B has been omitted from FIG. 8A for clarity;

FIGS. 9A and 9B are front and side elevation views, respectively, of afurther alternative embodiment of the prosthesis of the presentinvention;

FIG. 10 is a side view showing implantation of a tubular graft with theprosthesis of FIG. 9A;

FIGS. 11A and 11B are plan and side views, respectively, of anotheralternative embodiment of the prosthesis of the present invention;

FIG. 12 is a perspective view of another a still further alternativeembodiment of a prosthesis constructed in accordance present invention;

FIGS. 13A and 13B are end views showing the prosthesis of FIG. 12 in itscontracted state and expanded state, respectively;

FIGS. 14A and 1-4B are, respectively, views of an embodiment of theprosthesis suitable for treating a bifurcated lumen in an uncoiledstate, and as deployed in a bifurcated lumen;

FIGS. 15A and 15B are views showing the steps of deploying theprosthesis of FIG. 14 to treat an aneurysm in a bifurcated lumen; and

FIGS. 16A and 16B are views showing the steps of deploying analternative embodiment of the prosthesis of FIG. 14 to treat an aneurysmin a bifurcated lumen.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides prostheses for treating aneurysms,obstructive disease of vessels and body organs, and arterio-venousfistulas, that overcome the limitations of previously knownminimally-invasive treatment systems. In particular, a prosthesisconstructed in accordance with the present invention provides alteredfluid flow through a section of a single or bifurcated body lumen with adevice that is simple, yet elegant in design, easy to deploy, is readilyscalable for use throughout the body, and provides the functionality ofan internal bandage.

Referring to FIG. 1, illustrative prosthesis 10 constructed inaccordance the present invention is described. Because prosthesis 20includes certain features of both conventional coiled sheet stents, asdescribed, for example, in U.S. Pat. No. 5,443,500 to Sigwart,incorporated herein by reference, and conventional synthetic tubulargrafts, it is referred to hereinafter as a “graft stent.”

Graft stent 20 comprises coiled sheet portion 21 including a resilientlattice or mesh onto which a layer of biocompatible graft material 22has been affixed. Graft material 22 may have a permeability selected toaddress a particular application, and may be impregnated with one ormore drugs to effect a desired treatment. Thus, for example, graftmaterial 22 may be selected to be fluid impervious for arterio-venousfistula applications, but may be selected to be semi-permeable forapplications where it is desired to permit nutrients to pass through thegraft material, yet prevent cell proliferation therethrough. In yetother applications, the graft material may include a porosity sufficientto maintain a pressure differential between fluids disposed on eitherside.

Graft stent 20 preferably comprises a biocompatible material, such as ashape-memory alloy (e.g., nickel-titanium), while biocompatible graftmaterial preferably comprises a PTFE or polyester fabric. Graft material22 is affixed to coiled sheet portion 21 by any of the methods describedhereinbelow, including biocompatible adhesive 23, by sintering, sutures,or any combination of thereof. Graft stent 20 may include a singlecoiled sheet portion sandwiched between multiple layers of graftmaterial, or a single layer of graft material sandwiched betweenmultiple coiled sheet portions.

In the embodiment of FIG. 1, graft material 22 is affixed to coiledsheet portion 21 so that the graft material is wound within the seriesof overlapping turns of the coiled sheet portion when the prosthesis iswound to a reduced-diameter delivery (or “contracted”) state, as shownin FIG. 2A. When the coil sheet portion is preferably biased to returnto its larger-diameter deployed (or “expanded”) state, as shown in FIG.2B. In alternative embodiments, described hereinbelow with respect toFIG. 12, graft material 22 may comprise a solid tube, so that coiledsheet portion 21 is affixed within the tubular graft along a portion ofthe circumference of the coiled sheet portion.

Referring to FIG. 3, coiled sheet portion 21 of graft stent 20 is showndisposed on a sheet of graft material 22 during a step in the process ofassembling graft stent 20. Coiled sheet portion 21 comprises a thin flatsheet of material, about 1.0 to 5.0 mils thick, which is formed into alattice having a multiplicity of openings 24, for example, by die andpunch, laser cutting or chemical etching. Openings 24 reduce the overallmass of the graft stent, provide some longitudinal flexibility when thegraft stent is contracted, and may be used to enhance fixation of thegraft material to the coiled sheet portion, as described hereinbelow.Openings 24 may be triangular-shaped, diamond-shaped, rectangular-shapedor circular-shaped, or any combination thereof, and are preferablyarranged in a lattice that provides about 50% open space or more.

Alternatively, coiled sheet portion 21 be formed from a plurality ofinterwoven wires that are welded together around the circumference ofthe coiled sheet portion, such as described in U.S. Pat. No. 5,007,926to Derbyshire, which is incorporated herein by reference. Theintersections of the wires also may be welded together, and the sheetmay be swaged to reduce its thickness.

In accordance with the present invention, coiled sheet portion 21 ofgraft stent 20 preferably includes one or more rows of teeth 25 adjacentto one edge that mate with openings 26 on an opposing overlapping edgeof the coiled sheet. Teeth 25 lock the graft stent at a selectedexpanded diameter, as described in the incorporated Sigwart andDerbyshire patents. This locking action provides a tight seal of thegraft material against the interior surface of the body lumen. When usedto treat obstructive vascular disease, the tight seal serves to retainpatency of the vessel and reduce the potential for embolization; forarterio-venous fistulas, the seal reduces shunted flow; for aneurysms,the seal reduces the risk of bypass flow around the edges of the graftstent. In a preferred embodiment, teeth 25 are sufficiently long toengage mating openings 26 so as to stretch any graft material coveringopenings 26, but without perforating that graft material.

Alternatively, graft stent 20 may be secured in place in the body lumenusing a coiled sheet portion that retains several overlapping turns evenin the expanded state, as described, for example, in U.S. Pat. No.5,306,294 to Winston et al.

Coiled sheet portion 21 may be formed from any biocompatible material,such as a thermal shape-memory polymer or metal, super-elastic materialsuch as a nickel-titanium alloy, or other biocompatible resilientmaterial such as a stainless steel, tantalum, platinum or tungstenalloy. In a preferred embodiments a nickel-titanium alloy is used thathas an austenite transition temperature slightly below body temperature,so that the coiled sheet portion exhibits super-elastic behavior whendeployed. Also in the preferred embodiment, the nickel-titanium coiledsheet portion is heat treated, using processes known in the art, foractivating the shape-memory effect of the material so that the coiledsheet portion has an expanded diameter in the austenite phase.

Coiled sheet portion 21 of graft stent 20 may be formed in a variety ofsizes depending upon the intended application. For example, a graftstent for use in the treatment of aneurysms of the abdominal aorta mayrequire a length of 8-12 cm and an expanded diameter of 2-4 cm, while agraft stent for use in a main branch artery, or the iliac arteries, mayrequire a length of 2-8 cm and an expanded diameter of 8-12 mm. Ofcourse, graft stents for use in other vessels, for example, to treat A-Vfistulas or obstructive disease, may be smaller. While graft stents foruse in vessels under about 2.0 cm may employ a single coiled sheetportion 21 (as shown in FIG. 3), in accordance with the presentinvention, multiple coiled sheet portions also may be used to builtlonger graft stents. In addition, as described hereinafter, the graftstent of the present invention may be advantageously used to anchor aconventional tubular graft in place across a large aneurysm.

Referring now to FIGS. 3 and 4A-4F, the process of making a graft stentin accordance with the present invention is described. While the graftstent of FIG. 3 comprises one coiled sheet portion 21, several suchcoiled sheet portions 21 may be laid side-by-side, thereby providing agraft stent with an overall length about several times that of graftstent 20 of FIG. 3. Coiled sheet portion 21 is disposed on a sheet ofbiocompatible graft material 22, such as PTFE or polyester fabric. Thecoiled sheet portion 21 is then fastened to the sheet of graft materialusing one or more of the methods described hereinbelow. Any excessportion of the sheet may then be trimmed away, for example, with a razorknife to form the completed graft stent. The graft stent is thensterilized, for example, using a conventional ethylene oxide process.

In a first method of construction, shown in FIG. 4A, coiled sheetportion 21 is coated with a thin layer of biocompatible adhesive 27 (forexample, with a brush or by dipping), such as a liquid polyurethaneresin or epoxy. Adhesive 27 preferably remains flexible when dry. Whilethe adhesive is still wet, coiled sheet portion 21 is positioned ongraft material 22 as shown in FIG. 3. When adhesive 27 dries, it bondscoiled-sheet portion 21 to graft material 22. If several unconnectedcoiled sheet portions are employed, adhesive 27 also provides a jointbetween the neighboring coiled sheet portions. Excess portions 28 ofgraft material 22 (for example, around the edges of coiled sheet portion21) may then be trimmed to complete assembly of the graft stent.

When finished, a graft stent constructed by the above-described processhas a cross-section similar to that depicted in FIG. 4A, in whichadhesive 27 forms a layer, preferably about 0.1 mil thick, that bondsgraft material 22 to the outer surface of coiled sheet portion 21.Adhesive 27 also extends slightly into openings 24. Applicant hasobserved that a layer of polyurethane adhesive, employed as describedabove with respect to FIGS. 3 and 4A, provides good column strength in agraft stent built from a plurality of separate coiled sheet portions.Accordingly, the graft stent of the present invention may be built up toany desired length using the process described hereinabove.

In FIG. 4B, a alternative method of making a graft stent by sinteringgraft material to a coiled sheet portion is described. In thisembodiment, coiled sheet portion 21 is sandwiched between two layers ofa biocompatible graft material 22′, such as PTFE. The assembly is thenheated to raise the graft material to a temperature at which the twolayers contact one another through the multiplicity of openings 24, andfuse or sinter together, thereby forming a waffle shape. Pressure may beapplied to the assembly during the heating process to accelerate thefusing or sintering step. In addition, sutures or a thin layer ofbiocompatible adhesive may be employed to retain the assembly togetherprior to the heat treatment. Consequently, the two layers of graftmaterial 22′ disposed on the opposite sides of coiled sheet portion 21form a single fused layer within which coiled sheet portion 21 isembedded.

In FIG. 4C another method of making a graft stent is described. In thismethod, the coiled sheet portion is dipped into a liquid polymer, suchas urethane. The coiled sheet portion is then withdrawn from the liquidpolymer so that the liquid forms a film 29 extending across themultiplicity of openings 24 in the coiled sheet portion 21. The coiledsheet portion may then be disposed on a section of graft material, as inthe first method described above, so that the coated stent portionadheres to the graft material. Alternatively, the liquid polymer film 29may be permitted to air dry without being bonded to a graft portion. Inthis latter embodiment, the polymer film itself serves as the graftmaterial.

With respect to FIG. 4D, yet another method of making a graft stent ofthe present invention is described. In the embodiment of FIG. 4D, graftstent 30 is formed by sewing or suturing coiled sheet portions 21 tograft material 22, with stitches or sutures 31 extending through some ofthe multiplicity of openings of the coiled sheet portion. In a preferredmethod, the coiled sheet portions are first dipped in a biocompatibleadhesive and adhered to the graft material to retain the graft materialin a desired relation to the coiled sheet portion. Biocompatiblestitches or sutures 31 are then applied by machine or by hand along theedges and at intervals along the graft material to affix the graftmaterial to the coiled sheet portion.

With respect to FIG. 4E, a graft stent is formed by first sewing twopieces of graft material 22 together along three sides to form a “pillowcase” structure. Coiled sheet portion 21 is then inserted within thepillow case structure, so that the edge carrying the locking teethprojects from the open edge. The graft material is then affixed tocoiled sheet portion 21 with single machine-stitched or hand-stitchedseam. The embodiment of FIG. 4D enables the graft material to experiencesome lateral movement with respect to the coiled sheet portion, whichmay be desirable in certain circumstances.

In FIG. 4F, a yet further alternative embodiment is the graft stent ofthe present invention is described. Graft stent 33 comprises a singlesheet of graft material 22 sandwiched between two coiled sheet portions21. Coiled sheet portions 21 may be glued together by a suitablebiocompatible adhesive, or stitched or sutured to one another, therebytrapping the graft material in between the coiled sheer portions.Alternatively, one of the coiled sheet portions may include projections,while the other includes mating sockets to accept the projections,thereby retaining the assembly together. The embodiment of FIG. 4F ofthe invention is particularly well-suited for addressing problemsrelating to in-situ swelling of graft material in prior art grafts,because swelling of the graft material is limited by the coiled sheetportions.

Advantageously, with respect to the above-described embodiments of thepresent invention, because the lattice of the coiled sheet portion doesnot undergo longitudinal or radial distortion during deployment, thegraft material of the graft stent of the present invention is notsubjected to stress or distortion that could lead to perforation of thegraft material during deployment and use.

In addition, as a further step of the manufacture of any of the aboveembodiments of the graft stent of the present invention, the graftmaterial may be impregnated with one or more drugs to achieve a desiredtreatment goal. For example, the outer surface of the graft stent maycoated with an anti-heparin drug, such as Proamine, to enhance clottingof blood captured outside the graft stent (for example, to promotethrombosis within an aneurysm or to prevent embolization of frangiblematerial from the vessel wall), and may include a coating of aheparin-type compound on the inner surface of the graft stent to reducethe risk of thrombosis within the vessel.

Referring now to FIGS. 5A-5C, the steps of deploying the graft stent ofthe present invention to treat an idealized aneurysm in a single lumenportion of a vessel are described. It will be understood, however, thatthe steps of deploying a graft stent to treat an A-V fistula orobstructive disease of a vessel or body-organ apply equally.

Graft stent 35 is formed using the components and the methods ofmanufacture described hereinabove. The graft stent is then rolled abouta mandrel in a direction indicated by arrow A in FIG. 3 (so that teeth25 are inside the coil) to a contracted state for delivery. As of coursewill be understood by one skilled in the art, graft stent is contractedto the reduced diameter by winding the coiled sheet portion to form aseries of overlapping turns. The contracted graft stent is then loadedinto a sheath for delivery, as described, for example, in Sigwart U.S.Pat. No. 5,443,500 or Garza et al. U.S. Pat. No. 4,665,918, theentireties of which are incorporated herein by reference, which retainsthe graft stent in its contracted diameter.

In FIG. 5A, graft stent 35 is shown rolled to its contracted state anddisposed within delivery system 40, such as described in theabove-incorporated Garza et al. patent. For clarity, the detail of thelattice of graft stent 35 is omitted in FIGS. 5A-5C. Delivery system 40includes catheter 41 having a central lumen for accepting guide wire 42,nose cone 43 and outer sheath 44. Delivery system 40 is inserted intobody lumen 200 to be treated, for example, having aneurysm 201, througha major vessel along guide wire 42, as is well-known in the art, untilthe mid-point of the graft stent is located within aneurysm 201.

Once the location of delivery system 40 is established, for example,using fluoroscopy and standard angiographic techniques, outer sheath 44of the delivery system is retracted to release graft stent 35 into bodylumen 200 so that it spans aneurysm 201. When released from outer sheath44, graft stent 35 unwinds at least partially to conform to the diameterof the body lumen.

With respect to FIG. 5B, mechanical expander 45, which may be a ballooncatheter 46 carrying compliant balloon 47, is transluminally insertedwithin graft stent 35 and expanded. As balloon 47 expands, graft stent35, the teeth on the inner edge ratchet across the openings in theopposing edge of the graft stent, so that the graft is locked atprogressively larger diameters (as seen in FIG. 2B). Balloon 47 may beinflated, for example, while visualized with conventional fluoroscopicand angiographic techniques, until graft stent 35 is expanded to adiameter at which the teeth of the coiled sheet portion positively lockthe graft stent against the healthy portions of body lumen 200 andprevent bypass flow through aneurysm 201.

Once graft stent 35 has been locked into position within body lumen 200,balloon 47 is contracted, and balloon catheter 46 is withdrawn from thebody lumen. Because the teeth interengage with the openings on theopposing overlapping edge of the graft stent, graft stent 35 retains theexpanded diameter attained during the step of the balloon expansion, asillustrated in FIG. 5C, and does recoil elastically to the shape assumedwhen initially released from outer sheath 44.

Importantly, because graft stent 35 is elastically expanded by unwindingfrom its rolled position, no stress is applied to the graft material,thereby reducing the risk of perforation. Moreover, since the graftstent of the present invention preferably comprises a coiled sheetportion formed from a super-elastic shape memory alloy, such as anickel-titanium alloy, the graft stent may be conformed to a wide rangeof body lumen diameters while providing adequate radial strength.

As also will be apparent to one of skill in the art, the graft stent ofthe embodiment of FIG. 1 is distinguished from other previously knownstent graft combinations in that while the graft material covers thestent, no bunching or gathering of the graft material occurs when thegraft stent is contracted to its delivery diameter. Instead, the graftmaterial is wound along with the coiled sheet portion of the graft stentto a contracted diameter for delivery, and features a longitudinal seamthat is closed only when the graft stent is fully deployed. Accordingly,the graft stent of the present invention may be contracted to extremelysmall diameters, enabling the use of grafts in vessels not accessibleusing previously known stent graft delivery systems.

Referring now to FIGS. 6 and 7, alternative embodiments of the coiledsheet portion of the inventive graft stent are described. Coiled sheetportion 50 of FIG. 6 comprises a plurality of elements 51 joined byserpentine articulations 52, while coiled sheet portion 55 of FIG. 7comprises a plurality of elements 56 joined by linear articulations 57.Coiled sheet portions 51 and 56 illustratively employ the lattice designof coiled sheet portion 11 of FIG. 2. Articulations 52 and 57 arecontemplated to give coiled sheet portions 50 and 55, respectively,greater flexibility for passing through tortuous body lumens.

FIGS. 8A and 8B provide a further alternative for creating graft stent60 for use in larger vessels. FIG. 8B depicts coiled sheet portion 61having a variable geometry of openings 62 in the mesh lattice. The meshshown is expected to provide greater flexibility for a large graftstent, for example, having a length about 10 cm and a diameter of 2-2cm. Coiled sheet portion 61 includes teeth 63 that mate with openings 64in opposing overlapping edge 65 of coiled sheet portion 61.

Coiled sheet portion 61 has suitable graft material 66 affixed to itsouter surface, using the methods of manufacture described hereinabove.When rolled in the direction indicated by arrows B in FIG. 8B, graftstent 60 forms the tubular member shown in FIG. 8A (detailed omitted),wherein overlapping edge 65 of the graft stent spirals around the outersurface of the prosthesis. Graft stent 60 of FIGS. 8A and 8B is deployedin a manner similar to that described above with respect to FIGS. 5A to5C. It is contemplated that the spiral nature of the overlapping edgewill advantageously distribute radial expansive forces around thecircumference of the graft stent, thus reducing the risk of buckling.

Referring now to FIGS. 9A and 9B, an further alternative embodiment ofthe present invention is described with respect to graft stent 70. InFIGS. 9 and 10 the lattice detail of coiled sheet portion 71 has beenomitted for clarity. Graft stent 70 preferably has graft material 72affixed to an interior surface of the coiled sheet portion 71 inmid-region 73. Coiled sheet portion 71 includes rows of radiallyprojecting barbs 74 on its outer surface in regions 75 and 76 adjacentthe ends of the graft stent.

Barbs 74 are oriented so that they freely permit expansion of the coiledsheet portion, but engage the interior of the body lumen to resistcontraction of the stent due to external radial compressive force. Barbs74 of graft stent 70 preferably are formed as part of the etching orpunching process during formation of the coiled sheet stent portion ofthe graft stent. Interlocking teeth 77 preferably are sharp enough topierce and protrude through graft material 72 when the graft stent 70 islocked into position by a dilatation member.

In FIG. 10, a pair of graft stents 70 a and 70 b are shown disposed intubular graft 78 to seal the tubular graft to the healthy tissueproximal and distal of aneurysm 210. Tubular graft 78 may be apreviously known fabric graft, constructed, for example, from apolyester material. Graft stents 70 a and 70 b are “directional” in thesense that graft stent 70 a preferably has barbs 74 a disposed on itsouter surface near its left hand end, whereas graft stent 70 b has barbs74 b disposed on its outer surface near its right hand end. It isexpected that graft stents 70 a and 70 b of the present invention willprovide positive sealing at the proximal and distal ends of the tubulargraft which has been unattainable heretofore.

With respect to FIGS. 11A and 11B, yet another alternative embodiment ofa graft stent of the present invention is described. Graft stent 80 issimilar in construction to the prosthesis of FIG. 1, except that duringthe manufacturing process, a length of graft material 22 is left alongthe exterior edge of the coiled sheet portion 21 to form flap 81. Asseen in FIG. 11B, when graft stent 80 is deployed in body lumen 220,flap 81 overlaps longitudinal seam 82 in of the graft stent for part ofan additional turn, for example, one-quarter to one-half the deployedcircumference.

In accordance with the present invention, flap 81 of graft stent 80performs three functions. First, the flap serves to seal longitudinalseam 82 to prevent leakage. Second, flap 81 serves to anchor themid-section of the coiled sheet portion 21 to prevent bowing of themidsection of the coiled sheet when deployed. Third, the length of theflap may be adjusted to control the rate at which the coiled sheetportion expands when the graft stent is deployed. In particular, if flap81 is selected to have a length of, for example, one-half of thedeployed circumference, it is expected that flap 81 will provide asliding resistance as the coiled sheet portion unwinds, therebycontrolling the rate at which the coiled sheet is deployed.

Referring to FIGS. 12, 13A and 13B, a still further embodiment of agraft stent is described. Graft stent 90 includes coiled sheet portion91 and graft material 92 that has its edges sewn together to form atube. Elastic filaments 93 may be disposed in the region of the tubeadjacent longitudinal seam 94 in coiled sheet portion 91 so that theslack portion of the tube forms folds 95. When deployed in a vessel,folds 95 are crushed against the vessel wall by coiled sheet portion 91.

To enable stent graft 90 to be wound to its contracted state, graftmaterial 92 is affixed to the exterior surface of coiled sheet portion91 along only the part of the circumference of the coiled sheet portionnearest edge 96. Thus, when wound to its contracted state, coiled sheetportion 92 is only partly wound within the overlapping turns of thecoiled sheet portion, and doubles back on itself in region 97.Alternatively, the non-affixed portion of graft material 92 may be woundagainst the coiled sheet portion in a direction opposite to that of thecoiled sheet portion.

As shown in FIG. 13B, when graft stent 90 is deployed to its expandedstate, elastic filaments 93 keep slack portions of the tube arranged infolds 95, thus permitting the graft material to be expanded when coiledsheet portion 91 is locked in position as described hereinabove withrespect to FIGS. 5A-5C. It is expected that by forming graft material 92into a tube (and thus eliminating the longitudinal seam in theembodiment of FIG. 1), the tendency of edge 96 to buckle outward whenunsupported over long distances will be reduced. The embodiment of FIG.12 is also expected to provide the advantages perceived for theembodiment of FIGS. 11A and 11B, described hereinabove.

Referring now to FIGS. 14A and 14B, an embodiment of a graft stentsuitable for use in treating a bifurcated lumen, illustratively theabdominal aorta, is described. In FIG. 14A, coiled sheet portion 101 ofgraft stent 100 forms a segment of an annulus having large circumferenceedge 102 and small circumference edge 103. When rolled to its coiledexpanded state, coiled sheet portion 101 forms a conical shape. Teeth104 are arranged along inner edge 105 of coiled sheet portion, andengage openings along edge 106 in the expanded state. Graft material 107is affixed to coiled sheet portion 101 as described hereinabove, andincludes an opening 108. Tubular graft 109, which may comprise abiocompatible material, is affixed to graft material 107 in alignmentwith opening 108, for example by stitches 110.

As shown in FIG. 14B, graft stent 100 may be coiled to form a tube anddeployed to its expanded state in bifurcated lumen 230 so that smallcircumference edge 103 is disposed in branch 231 and large circumferenceedge 102 is disposed in trunk 232. When deployed, as describedhereinbelow, tubular graft 109 extends into branch 233 of bifurcatedlumen 230, thereby excluding aneurysm 234 from the flow path.

With respect to FIGS. 14B, 15A and 15B, deployment of graft stent 100 isdescribed. In FIGS. 15A and 15B, to enhance clarity, the details of thecoiled sheet portion have been omitted and delivery sheath 120 isillustrated as being transparent. In FIG. 15A, graft stent 100 is showndisposed in delivery sheath 120 and is coiled to its contracted state.Tubular graft 109 is folded against graft stent 100 so that the end ofthe tubular graft is located near distal end 121 of delivery sheath 120.Suture 111 forms a loop through end 112 of tubular graft 109. Push rod122 is disposed in delivery sheath 120 and retains the graft stent 100in position while delivery sheath 120 is retracted proximally.

Delivery system 120 as depicted in FIG. 15A is inserted transluminallyinto the bifurcated lumen via one of the branches. For example, in FIG.14B, delivery system 120 may be inserted via branch 231 (e.g, the leftfemoral artery), so that distal end 121 of delivery system 120 isdisposed in trunk 232 of the bifurcated lumen 230. A guide wire may thenbe inserted via the contralateral branch 233 and used to snare suture111. Suture 111 is then brought out through the contralateral branchaccess site.

With respect to FIG. 15B, push rod 122 is used to retain graft stent 100in a predetermined position relative to bifurcated lumen 230, whiledelivery sheath 120 is retracted. This step permits tubular graft 109 tobe fully exposed, so that it does not contact distal end 121 of deliverysystem 120. Suture 111 is used to manipulate tubular graft 109 intoposition in branch 233. Push rod 122 is again employed to maintain graftstent 100 in position while delivery sheath 120 is fully withdrawn.

Once delivery sheath 120 is withdrawn, coiled sheet portion 101 of theprosthesis expands to its expanded state. As described hereinabove withrespect to FIG. 5B, a balloon dilatation system may then be inflatedwithin coiled sheet portion 101 to lock graft stent 100 in position. Theloop formed by suture 111 is then cut, and the suture material pulledthrough end 112 and out of the patient's body. When fully deployed, thegraft stent excludes aneurysm 234 from the flow path of bifurcated lumen230. In addition, an additional previously known stent, such asdescribed in the above incorporated Sigwart patent, may be employed toaffix end 112 of graft stent 100 is place.

Referring to FIGS. 16A and 16B, an alternative to the embodiment of FIG.14 is described for treating an aneurysm in bifurcated lumen 230. Graftstent 130 comprises a rectangular or annular segment-shaped coiled sheetportion 131 having graft material 132 affixed to it using any of theprocesses described hereinabove. Instead of tubular graft 109 of theembodiment of FIG. 14, however, graft stent 130 includes docking neck133 attached in alignment with the opening in graft material 132 viasutures 134. Docking neck 133 may include radiopaque filaments embeddedwithin it so that graft stent 130 can be deployed with docking neckoriented in alignment with branch 233, as determined, for example, byfluoroscopy.

A delivery system similar to that of FIG. 15A is first used to deploygraft stent 130 so that it extends from trunk 232 to branch 231 ofbifurcated lumen 230. After graft stent 130 has been locked intoposition, a second delivery sheath containing graft stent 140,constructed as described with respect to FIG. 1 or FIG. 12, is insertedthrough contralateral branch 233. Graft stent 140 is then deployed sothat distal end 141 is disposed in docking neck 133 of graft stent 130and proximal end 142 is disposed in branch 233. Graft stent 140 isdeployed as previously described. Accordingly, graft stents 130 and 140may be assembled in-situ to exclude aneurysm 234 in bifurcated lumen230.

As will of course be understood, graft stents suitable for use intreating diseased bifurcated lumens may be constructed using any of theprocesses described hereinabove. In particular, the graft material mayeither include a longitudinal seam, a flap of excess material, asdescribed with respect to the embodiment of FIG. 11A, or a tube, asdescribed for the embodiment of FIG. 12.

While preferred illustrative embodiments of the invention are describedabove, it will be apparent to one skilled in the art that variouschanges and modifications may be made therein without departing from theinvention and it is intended in the appended claims to cover all suchchanges and modifications which fall within the true spirit and scope ofthe invention.

1. A coiled graft stent having a contracted state with a first diameterand an expanded state with a second diameter, the second diameter beinggreater than the first diameter, the prosthesis expandable to theexpanded state when released from the contracted state, the prosthesiscomprising: a first sheet of stent material; and a graft materialaffixed to the first sheet of stent material, wherein when the coiledgraft stent is in the contracted state the first sheet of stent materialand the graft affixed thereto form a series of overlapping turns andwherein when the coiled graft stent is in the expanded state the graftmaterial includes a flap that extends from a longitudinal edge of thefirst sheet of stent material.
 2. The coiled graft stent of claim 1,wherein the flap extends a length equal to about one-quarter to one-halfthe circumference of the first coiled sheet stent in the expanded state.3. The coiled graft stent of claim 1, wherein the graft material isimpregnated with at least one drug.
 4. The coiled graft stent of claim1, wherein the graft material includes a semi-permeable portion thatpermits nutrients to pass therethrough while preventing cellproliferation therethrough.
 5. The coiled graft stent of claim 1,wherein the graft material includes a polyester material.
 6. The coiledgraft stent of claim 1, the first sheet of stent material having anouter surface, the graft being affixed to a first portion of the outersurface of the first coiled sheet stent, wherein a second portion of theouter surface of the first sheet of stent material includes a pluralityof outwardly directed projections.
 7. The coiled graft stent of claim 1,further comprising a second sheet of stent material, the graft materialbeing interposed between the first and second sheets of stent material,wherein when the coiled graft stent is in the contracted state the firstand second sheets of stent material and the graft affixed thereto form aseries of overlapping turns.
 8. The coiled graft stent of claim 1,wherein the first sheet of stent material includes a plurality ofopenings and a plurality of teeth adjacent to an inner edge of the firstsheet of stent material, the plurality of teeth interengaging theplurality of openings to lock the first sheet of stent material in theexpanded state.
 9. The coiled graft stent of claim 1, wherein the firstsheet of stent material comprises a plurality of sections, each sectioncomprising a plurality of openings, adjacent sections being joined byarticulations.
 10. A prosthesis for treating a section of a body lumencomprising: a stent portion, the stent portion comprising a first sheetof stent material, the stent portion having a contracted state whereinthe stent portion is wound to a first diameter to form a series ofoverlapping turns, and an expanded state wherein the stent portion has asecond diameter greater than the first diameter, the stent portionexpandable to the expanded state when released from the contractedstate; and a graft material, the graft material affixed to the stentportion, wherein a portion of the graft material is wound within theseries of overlapping turns of the stent portion when the stent portionis in the contracted state, and the graft material includes asemi-permeable portion that permits nutrients to pass therethrough whilepreventing cell proliferation therethrough.
 11. The prosthesis of claim10, the prosthesis has an outer surface, a portion of the outer surfacebeing formed by the stent portion, wherein the portion of the outersurface of the prosthesis formed by the stent portion includes aplurality of outwardly directed projections.
 12. The prosthesis of claim10, wherein the stent portion further comprises a second sheet of stentmaterial, the graft material being interposed between the first andsecond sheets of stent material.
 13. The prosthesis of claim 10, whereinthe stent portion includes a plurality of openings and a plurality ofteeth adjacent an inner edge of the stent portion, the plurality ofteeth interengaging the plurality of openings to lock the stent portionin the expanded state.
 14. The prosthesis of claim 10, wherein the stentportion comprises a plurality of elements joined by articulations.
 15. Aprosthesis for treating a section of a body lumen comprising: a firstcoiled sheet comprising a shape-memory material, the first coiled sheethaving a contracted state wherein the first coiled sheet is wound to afirst diameter to form a series of overlapping turns, and an expandedstate wherein the first coiled sheet has a second diameter greater thanthe first diameter, the first coiled sheet expandable to the expandedstate when released from the contracted state; and a graft materialaffixed to the coiled sheet wherein a portion of the graft material iswound within the series of overlapping turns of the first coiled sheetwhen the first coiled sheet is in the contracted state.
 16. Theprosthesis of claim 15, wherein the first coiled sheet comprisesnickel-titanium alloy.
 17. The prosthesis of claim 15, wherein the firstcoiled sheet comprises a portion defining a multiplicity of openings.18. The prosthesis of claim 17, wherein the multiplicity of openings arearranged in a lattice that provides at least 50 percent open space. 19.The prosthesis of claim 17, wherein the graft material comprises firstand second layers that are affixed to one another through themultiplicity of openings of the first coiled sheet.
 20. The prosthesisof claim 15, wherein the graft material is impregnated with at least onedrug.
 21. The prosthesis of claim 15, wherein the graft materialincludes a semi-permeable portion that permits nutrients to passtherethrough while preventing cell proliferation therethrough.
 22. Theprosthesis of claim 15, further comprising a second coiled sheetcomprising a shape-memory material, the graft material being interposedbetween the first and second coiled sheets.